The ANC alleged that the dismissal of Bantom meant that Morkel stood to benefit due to his father serving as premier.
Morkel denied this claim and was a councillor candidate for the newly created DA instead.
In June 2005, Morkel was accused of accepting bribes from the company Gilt Edged Management Services (Gems).
The defections were announced at a press conference headed by ANC national chairperson Mosiuoa Lekota.
The agreement between Arendse and Morkel was discussed before the Erasmus Commission of Inquiry into allegations of spying in the Cape Town City Council.